Begin by crushing the freeze-dried blueberries into a fine powder using a food processor or a zip-top bag with a rolling pin.

In a medium saucepan, melt together the white chocolate chips, unsalted butter, and cream cheese over low heat.

Remove the melted mixture from the heat and stir in the fresh lemon juice, lemon zest, vanilla extract, and a pinch of salt.

In a large mixing bowl, pour in the Rice Chex cereal and drizzle the melted mixture over it.

Fold in the crushed freeze-dried blueberry powder until evenly distributed.

Transfer the coated mixture into a large zip-top bag along with the powdered sugar and shake until completely coated.

Spread the puppy chow on a parchment-lined baking sheet and let it cool for about 10 minutes.